1. Field of the Invention
This invention is directed to the field of medical optical imaging.
2. Description of the Related Art
In optical coherence tomography, a sectional image of an object is obtained in that a light beam scans the object along a line (e.g., along a straight line on the surface). This scanning movement gives (for example) the x-coordinate of the image. In every x-position along this line, the light beam also penetrates into the object. A tomographic interferometer measures the depth z from which light of intensity I is reflected. In this way, a tomographic image I(x,z) of the object is obtained. This imaging process was first described in the article "Optical Coherence Tomography", Huang, D; Swanson, E. A.; Lin, C. P.; Schuman, J. S.; Stinson, W. G.; Chang, W.; Hee, M. R.; Flotte, T.; Gregory, K.; Puliafito, C. A.; Fujimoto, J., Science, volume 254, 1991, pages 1178-1181.
In this method--as in classical reflected-light microscopy--spatially high-frequency modulations of the scattering potential (this corresponds roughly to the complex refractive index) act as image-generating structures. Whereas optical contrasting methods such as phase contrast and interference contrast have been developed in conventional microscopy to improve visibility of tissue structures, suitable methods for coherence tomography have not yet been discovered.